Letoff control mechanism



June 17, 1958 wms ow ET AL 2,838,921

LETOFF CONTROL MECHANISM 4 Sheets-Sheet 2 Filed Aug. 26, 1953 INVENTOR.

M861 6. Wl/YSLOW y MORRIS M W/IZOAOP fan/nod 6' '4 TTTORNEYS LETOFF CONTROL MECHANHSM Application August a, 1953, sw rm. 376,650

9 Claims. or. 66-86) .This invention relates generally to letoif means'for regulating the withdrawal of a convolutely wound or spooled element, and more particularly to an improved control mechanism for such letoifmeans.

- While the control mechanisrn 'of the present invention may be used to goodadvantagewherever a letoif means is employed, it is especially useful in warp knitting machines where it is highly important to maintain an even and uniform yarn tension at the knitting means to avoid so-called shade marks in the fabric being knitted, and the invention is accordingly described below for purposes of convenient illustration mainly in relation to its adaption for this purpose v Briefly described, the control mechanism of the present invention is characterized by the arrangement of a three component planetary gear-train, having all of the components movably mounted, with two of the components connected for comparing by relative movement the v United StatesPatent O 2 for the purpose of maintaining a uniform linear letoff speed of the warp yarns as they are withdrawn for knitting. There have been numerous prior proposals for controlling the regulating devices R and R so that this speed compensation is obtained evenly and smoothly, but characteristic troubles with huntingin the controls and with control reaction lag have still remained.

The letofi control device or mechanism of the present invention, which is designated generally in the drawings by the reference numeral it), eliminates these prior art difficulties, and further provides a much simpler control means than has heretofore been commonly employed. This letoff control device ltl'operates, as previously mentioned in general, by comparing the operating speed of the drive shaft Dlwith the linear warp yarn letoff speed,

a as indicated by slave yarns S and S trained from. yarn packages P and P past the control device 10 and over the warp beams W and W to pass forward to the knitting means (not shown) with the rest of the warp yarns; and by adjusting the speed regulating devices R and R from this comparison to maintain a constant comparative relation.

Thearrangernent of the letoff control device 10 by which it is adapted to operate in the above noted manner is illustrated in detail by Figs. '3 to 6 of the drawings,

and from which it will be seen to comprise a first input operating speed of the letoff drive means andv the linear letoff means is obtained that is free of hunting or reaction lags, and that requires a very small power input so that it may be readily and effectively operated with sleeve yarns.

These and other features of the present invention are described in further detail below in connection with the accompanying drawings, in which:

Fig. 1 is a side elevation of a representative warp knitting machine (without any showing of the knitting means) incorporating a letoff control mechanism arranged according to the present invention;

Fig. 2 is a fragmentary rear elevation (i. e., from the left) of the warp knitting machine shown in Fig. 1;

Fig. 3 is an enlarged side elevation of the letoff control mechanism from the left as seen in Fig. 2;

Fig. 4 is a plan view of the letoff control mechanism shown in Fig. 3 with the cover plate removed; 5

Fig. 5 is a sectional detail taken substantially on the line 5-5 in Fig. 4; and a Fig. 6 is a sectional detail taken substantially on the line 66 in Fig. 4. t t

The warp knitting machine illustrated in Fig. l is of a generally conventional and representative form, the machine frame F being shown arranged to carry beams of warp knitting yarns as at W and W, which may be made up in sections as shown in Fig. 2, and the camshaft C for the knitting machine being connected to rotate a drive shaft D from which the letoff motion of each warp beam W and W is driven separately through variable speed regulating devices R and R..

The speed regulating devices R and R are provided to allow adjustment of the speed: at which the warp beams W and W are driven from the shaft D in order to make possible a compensatingincrease in beam speed drive shaft 12 journalled in the housing for the device,

dence with the number of warp beams Wand W.

The first input drive shaft 12 is made responsive to the operating speed of the letoff drive shaft D, as driven fromthe camshaft C, by .means of a two stage chain and sprocket driving connection extending from the drive shaft D, as indicated at 16 and 18 in Fig. 2, to a sprocket pulley element 20 carried on the input shaft 12. The input shaft 12 is also fitted with a worm 22 engaginga worm wheel 24 that is fixed at the lower end of a stub shaft 26 supported by a bearing plate 28 arranged inside the device housing;

The bearing plate 28 also supports in spaced relation a series of further stub shafts 3h, 32, 34 and 34' (compare Figs. 4 and 5). The stub shaft 30 carries a spur gear 36 that runs in engagement with a spur gear 38 arranged on the stub shaft 26 just above the worm wheel 24, and that also engages a spur gear 46 arranged at the lowerend of the stub shaft 32, this spur gear iii being identical with the gear 38 except that it is formed with a cam surface 42 at its lower face to operate a plunger pump 44 for circulating lubricant within the control device housing through distributing lines such as are indicated at 46 and 46. Both of" the stub shafts 26 and 32 are mounted on the bearing plate 28 in bushings 26 and 32, and carry identical spur gears 43 and 48 at their upper ends. Also, identical brackets 56 and Sit are pivoted around the stub shaft bushings 32 and 26' and arranged for adjustment to serve as mounting means for change gear tandems 52 and 52 engaging respectively the upper spur gears 48 and d8 onstub shafts 32 and 26; and spur. gears 54 and 54 carried'at the upper end of. stub shafts 34 and 34.- i

The stub shafts 34 and 34 are elements of the previously mentioned planetary gear trains that characterize the operating arrangement of the letoif control device of the present invention, the sun gears 56 and 56 of these gear trains being carried adjacent the lower ends of stub shafts 34 and 34. The related planet gears 58 and 58' are also carried on the stub shafts 34 and 34 by means of bearing sleeves 6i) andll having radial mounting arm portions 62 58 and (compare Figs. 4 and 6).

It will be noted from the description so far of the control device operating elementsthat the sun gears 56 and 60 and 60' to engage worms 66 and 66 on the second input drive shafts 14 and 14'. Thesesecond input drive shafts 14 and 141 are in turn fitted with friction drum; or pulleys 68 and 68 adapted to be driven by the slave yarns S and S when these yarns are Wrapped there around; and as the slave yarn S and S are further trained around the warp beams W and W to be letofi. just as any other warp yarn is, the result is to rotate the second input drive shafts 14 and 14 through the friction drums 68 and 68' in relation to thelinear letoff speed. Accordingly, as long as the linear letoff speed is such as to cause planetary movement of the planet gears 53 and 58' in relation to the driven sun gears 56 and 56 so that a pure rolling motion results at the pitch circles of the mating sun and planet gears 56 and 58, and 56 and 58, then no reaction will result at the planet gears 58 or 58', but whenever this is not so there will be a resulting reaction that may be transmitted to cause movement of ring gears 70 and 70 forming the third component of the planetary gear trains.

These ring gears 70 and 70 are rotatably disposed, together with bevel gears 72 and 72', in supporting bracket structures asat 74 and 74' adjacent the lower end of stuff shafts 34 and 34' and coaxially therewith. Each of the bevel gears 72 and 72 are engaged by mating bevel gears 76 and 76' which are carried on output 'shafts '78 and 78' journalled in the control device housing and extending therefrom for transmitting the resulting movement of the ring gears 70 and 79 to adjust the speed regulating devices R and R through suitable actuating linkages as indicated at L and L (compare Figs'l and 2).

The change gears 52 and 52' provided in the drive gear trains to the planetary sun gears 56 and 56 make it possible to set the control device for any relation desired between the letoff operating speed and the linear warp yarn letoff speed, and once this relation has been set the planetary gear trains react instantly and continuously at the ring gears 70 and 70 to signal any variation from this relation so that immediate correction can be made. In addition, the reaction at the ring gears 70 and 70 is not such as to involve any substantial inertia efiect in making the necessary corrective adjustment, so that there is no tendency in the mechanism to overrun and result in hunting as the adjustment is made. Furthermore, the worm drive connections at each of the input shafts 12, 14- and 14' allow operation of the control device at a very small power requirement, so that the device can be incorporated in a letoff drive without any modification WhltGVI in the driving power nor mally available while still providing excellent control of the linear letoff speed.

The present invention has been described in detail above for purposes of illustration only and is not intended to be limited by this description or otherwise except as defined in the appended claims.

' We claim:

1. The combination with a warp letotf mechanism incorporating an adjustable drive means governing the linear letoff speed, of a control means for said letofi mechanism comprising, a sun gear, a planet gear and a ring gear forming a three component planetary gear train in which all of the components are movably mounted, driving and 62 for the planet gears A; I means for one of said components responsive to the operating speed of said drive means, driving means for another of said components responsive to the linear letoif speed, andmeans connecting the third component of said planetary gear train for adjusting said drive means from the movement of said third component resulting from the relative movement of the first two components of said gear train.

2. In a warp knitting machine having a warp beam and adjustable 'letoif drive means therefor, a control mechanism for adjusting said drive meansto maintain a constant linear letoif speed from said warp beam, said control mechanism comprising a first inputj'drive responsive to the operating speed of said drive'means, a second input drive responsive to the linear letotf speed from said warp beam, a sun gear, a planet gear and a ring' gear forming a three component planetary gear train having all of the components thereof movably mounted, means connecting said sun gear and said planet gear respectively for comparing by relative movement the responses of said first and second input drives,-and means connecting said drive means for adjustment from the resulting movement of the third ring gear component of said planetary gear train.

3. In a warp knitting machine having a warp beam and a letoff drive means adjustably coupled with said warp beam, a control mechanism for adjusting the coupling of said drive means to maintain a constant linear letoif speed from said warp beam, said control mechanism comprising first and second input drive shafts, a

three component planetary gear train having all of the elements thereof movably mounted, means including a Worm on each of said first and second input drive shafts and worm wheel-s engaging each of said worms and con necting two of said components for movement respectively by said first and second input drive shafts, means connecting the third of said components for adjusting the coupling of said drive means from the resulting movement of said third component, and means driving said first and second input drive shafts in relation respectively to the operating speed of said drive means and the linear letoff speed from said warp beam.

4. In a warp knitting machine, the structure defined in claim 3 and further characterized in that said first input drive shaft is fitted with a pulley element for driving connection with said drive means, and said second input drive shaft is fitted with a friction drum for driving from a slave yarn trained over said drum in series with said warp beam.

5. In a warp knitting machine, the structure defined in claim 3 and further characterized in that said drive means comprises the knitting machine cam shaft, and a variable speed mechanism is interposed for coupling said drive means to said warp beam.

6. In a warp knitting machine, the structure defined in claim 3 and further characterized in that more than one warp beam is employed, said drive means is adjustably coupled separately to each warp beam, and said second input drive shaft, planetary gear train, and connecting means for adjusting the coupling of said drive means are duplicated for each warp beam.

7. A letoif control mechanism for warp knitting machines and the like, said mechanism comprising, in combination with an adjustable letofi drive means, a sun gear, a planet'gear and a ring gear forming a three component planetary gear train and arranged with all of the components movably mounted, means for driving one of said components in relation to the operating speed of said letofi driving means, means for driving another of said components in comparable relation to the linear letofli speed resulting from the operation of said letofi drive means, and means connecting said drive means for adjustment from any resulting movement of the third component of said gear train.

8. A letoff control mechanism as defined in claim 7 and further characterized in that the means connecting said drive means for adjustment from any resulting movement of the third component of said gear train comprises a mechanical linkage reaching from said third com ponent to said drive means. I

9. A letoff control mechanism as defined in claim 7 and further characterized in that the means for driving another of said components in comparable relation to the linear letotf speed resulting from the operation of said letoif drive means comprises a roll member peripherally engaged for rotating at said linear letotf speed.

References Cited in the file of this patent UNITED STATES PATENTS Sawyer Apr. 16,1918 Tolnai Nov. 18, 1941 Fiorentino Feb. 5, 1946 Duer June 17-, 1947 Lear Feb. 24, 1948 Lambach Aug. 31, 1948 Henry May 27, 1952 Morrison et al. June 10, 1952 Lambach Jan. 5, 1954 

